Interesting Subject
Basically, I agree with the concept that this scenario is an exercise in risk management as opposed to a "legal" question. "One Level of Safety" does not in fact exist. That is why we do not have One Regulation that applies to this issue with which everyone must comply. From a safety perspective it makes little sense to have different rules based on whether one operates under Part 91, 135 or 121, but we do. The issue is economicis or more simply money. The rule maker (FAA) has a conflict of interest, the law requires it to establish safety rules but at the same time makes the Agency responsible for "economic viability" of its regulatory decisions. This is evident, to different degree, in all of the Regs (91, 135, & 121).
Think of these hypothetical scenarios.
Under 121, accelerate/stop and accelerate/go are both required by the Regs. When this adversely affects the potential operation a series of "variants" are permitted, e.g., balanced field vs. unbalanced field; the use of clearways, changes in heading, etc., and special exceptions granted on an individual basis. This is why Boeing 737's are not "grounded" when there are known anomalies in its rudder system that were not "fixed". The body count wasn't high enough to "justify" the grounding vs. the economic loss that would have occurred. So we continued to fly them while we guessed at how to "fix" them. The same thought process was applied to the propeller problems experience by the EMB-120 and the inadequacy of ice detection and elimination in the ATR. Money vs. Safety, more often than not, errs in favor of money.
Under 135, we see similar scenarios (in the area of takeoff performance) but most importantly, the aircraft is "assumed" by the FAA to be capable of flying through obstructions in the flight path as opposed to over obstructions (121). Very different. Common sense tells you that no aircraft can successfully fly through an obstruction without an "accident". Nevertheless, the FAA "approves" procedures that assume it can. Why? Because if they did not, those aircraft would cease to operate. They simply are not capable of complying with 121 and, due to economic considerations we create 135 and attempt to "manage the risk" by presuming that many engines just aren't going to "quit" in that particular area of the operation. Statistically they don't. If it is not your day and you crash because of this, you will merely become a "bump" in the statistics and nothing will change. In the opinion of the FAA, the "risk" is adequately managed. The Public, which knows nothing about any of this, doesn't have a clue that there is more than "one level of safety". In fact they are deliberately led to believe that they are being "protected" by the Agency. In fact, they are not; certainly not to the same degree.
Under 91, very nearly any risk that you choose to take is permitted under the law. The FAA changes its focus and shifts the "burden" from itself, to the pilot or operator. Why do you think they have 91.13? That is nothing more than a CYA program designed to protect the Agency from it's failure to accept responsibility. If the same rules (121) were applied to "light twins" many if not most of them would never fly. Their "single-engine" peformance is either non-existant or so marginal as to be irrelevant in the takeoff/climb out phase. They can't climb over obstructions on one engine, so what does it matter if they can't accelerate and stop either? The only thing that will change in that scenario is the physical point of impact. In the eyes of the FAA it's perfectly OK for you to kill yourself if you want to and if someone tries to blame them well, your "careless and reckless" operation will cover their butts, courtesy of 91.13. Part 91 is a classic case of tokenism. When a little airplane doesn't make it, the body count doesn't make the front page and you don't see it on FOX news for a week. In fact you don't see it at all, unless some big-wig happens to be on board.
I'm not suggesting what anyone should do but I will say that my own decisions are not based on some rule in a book. Yes, I follow the law but my decisions are based on my judgement which is tempered by my experience. The Regs expect this to a certain extent. That is why we give the PIC the authority to deviate from any rule in the interest of safety. Uner Part 91, what is "safe" and what is not rests mainly on the shoulders of the PIC and not the FAR's. That may be a cynical view, but it's pretty close to the mark.
To the maker of the thread: I believe it is legal for you to depart without accelerate/stop. Your "risk" is much higher in the accelerate/go phase of flight --- you will NOT be able to climb over most obstructions in any light twin (with and engine failure), but you aren't even required to consider that. If you were required to consider it, the data you have available makes it impossible to do so. You don't really have a clue as to where the obstructions are or how high they might be on any runway. Bottom line: If you're not comfortable, don't do it. The life you save will be your own. That's more valuable than any job and more importan than any FAR.
